The present invention relates to degassing a liquid, and more particularly to vacuum degassing a liquid.
Degassing is practiced in liquid chromatography to extract air from mobile phase solvents since the pressure of air (particularly oxygen) interferes with chromatographic analysis. See Bakalyar, Bradley and Honganen, The Role of Dissolved Gases in High-Performance Liquid Chromatography, Journal of Chromatography, 158 (1978) 277-293. In prior art systems, as shown in FIG. 1, solvent is conducted from a bottle 140 via tubing 150 to a degasser 170 where the solvent is degassed. The degassed solvent is conducted from the degasser 170 via tubing 172 to a liquid chromatography analytical system (LC analytical system) 180 for use as a mobile phase.
FIG. 2 shows a schematic diagram of a Shodex DEGAS KT-Series Degasser 170 available from Shodex Group of Tokyo, Japan. To degas the solvent, degasser 170 includes a vacuum chamber 284 and a vacuum pump 286 to create a vacuum therein. The solvent is pumped by a liquid chromatography pump (which pump is not shown in FIG. 2) from bottle 140 via tubing 150 to the vacuum chamber 284. In the vacuum chamber 284, the solvent flows through tubing 287. As the solvent flows therethrough, gas dissolved in the solvent goes out through the wall of tubing 287, which is made of a special macromolecular film, and the solvent is thus degassed. A heater 288 under a vacuum chamber base 290 can be used to heat the solvent in vacuum chamber 284 which increases the effectiveness of degassing. The degassed solvent is further pumped from vacuum chamber 284 to a LC analytical system (not shown in FIG. 2) via tubing 292. See Shodex Operation Manual No. 781 for Shodex DEGAS KT-Series Degassing Device available from SHOWA DENKO K.K., Specialty Chemicals Division, Shodex (Separation & HPLC) Group, 13-9, Shiba Daimon 1-Chome, Minato-ku, Tokyo 105, Japan.1110
Shodex degasser 170 of FIG. 2 can be used to degas components of a mixed solvent as is schematically shown in FIG. 3. Each of bottles 300, 302 and 304 contains a component of the solvent. The components are conducted via respective tubings 308, 310 and 312 through degasser 170 wherein each component is degassed as it passes through. Thereafter, in a portion 316 of tubing, the degassed components are mixed into a solvent which is conducted to a liquid chromatography analytical system (not shown in FIG. 3) via tubing 318.
It is desirable to provide effective methods and apparatus for degassing a liquid.